Dual-channel piezoelectric injector

ABSTRACT

The invention discloses a dual-channel piezoelectric injector, including a dual-channel injector body, its bottom in turn is connected with an upper intermediate, a lower intermediate and a dual-channel needle valve body. At the top of the dual-channel injector body there are two tubing interfaces, and each tubing interface has a tubing fuel duct. There are two laminated piezoelectric actuators and two spray fuel ducts connected to two tubing fuel ducts respectively inside the dual-channel injector body. The upper intermediate and lower intermediate connected with each other to form the middle connection body. From top to bottom of the middle connection body, there is an external control fuel duct, an external spray fuel duct, an internal control fuel duct and internal fuel spray duct. Inside the double-channel needle valve body, there is the sleeve structure of the needle valve hole, at the bottom of double-channel needle valve body there is an internal fuel spray nozzle connecting the internal casing hole which is outside the body, and an external fuel spray nozzle connecting to the external casing hole which is outside the body. Through the two laminated type piezoelectric actuators, control is realized for the pressure difference between the fuel pressure of the fuel control cavity and the fuel pressure of the inner pressure chamber or outer pressure chamber. So it is also realized to control the open or close state of the internal or external needle valve, in turn to control the injection action of the internal fuel spray nozzle or external fuel spray nozzle. The present invention has a simple structure and a low manufacturing cost.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from CN Application No. CN201310081487.6, filed Mar. 14, 2013 and PCT Application No.PCT/CN2013/083664, filed Sep. 17, 2013, the contents of which areincorporated herein in the entirety by reference.

FIELD OF THE INVENTION

The invention introduces a dual-channel piezoelectric injector, which isapplied to the high pressure common rail electronically controlled fuelinjection system in the dual-fuel engine or the high pressure commonrail electronically controlled fuel injection system in the dual-railengine, and especially applied to the dual fuel engine or dual commonrail engine.

BACKGROUND OF THE INVENTION

With the energy depletion and environmental pollution worseninggradually, the development of the internal combustion engine industryshows a trend of spurt, various new-type combustion technologies emergein an endless stream, and then dual-fuel combustion technology appears.With the development of electronic technology and the improvement ofinternal combustion engine design, diesel technology, gasolinetechnology and dual-fuel engine technologies such as gasoline/naturalgas dual-fuel engine, natural gas /diesel dual-fuel engine,gasoline/diesel dual-fuel engine, biodiesel/diesel dual-fuel engine havebeen developed rapidly.

Since the cylinder combustion status of the internal combustion engineaffects the comprehensive performance of engine directly, so organizinginjection reasonably and further controlling cylinder combustion are themost direct and effective way to improve the engine performance.Currently, the fuel injection system applied to the dual-fuel engine ismostly the dual-injector system, that is, two injectors are mounted inthree different ways to realize different methods of injection: Thefirst way is that a fuel injector is installed on the intake manifold,while another one is installed on the cylinder head to make one fuelinjected on the intake manifold and another injected in cylinder. Thesecond way is that two injectors are all installed on the intakemanifold, to make both fuel injected on the intake manifold. The thirdway is that two injectors are all installed on the cylinder head, tomake both fuel injected in cylinder.

The first two of the three injection ways can be achieved by modifyingthe existing single fuel injector engine, but the physicalcharacteristics of fuel have specific restriction, that is the fuelinjected external cylinder has high volatility.

The third way has broad development prospects as the physical propertiesof fuel have no restriction. But this way makes the structure ofcylinder head become complex, so modifying the existing single injectorengine becomes especially difficult and also makes the manufacturingcost increased.

At present, there are some dual-channel injectors in the market, butthey are very complex and the installation of them needs to change thecylinder head.

SUMMARY OF THE INVENTIONS

The purpose of the invention is to overcome prior art technical problemsand shortages, and provide a dual-channel piezoelectric injector appliedto dual-fuel engine or dual-rail engine.

In order to solve the above technical problems, the dual-channelpiezoelectric injector is designed as follows:

Including dual-channel injector body, its characteristics are at thebottom of the injector body successively connected with upperintermediate, lower intermediate and the double-channel needle valvebody; At the top of the dual-channel injector body above has two tubinginterfaces, and each tubing interface has a tubing fuel duct. There aretwo laminated piezoelectric actuators and two spray fuel ductsconnecting two tubing fuel ducts respectively in the dual-channelinjector body.

The upper intermediate and the lower intermediate are connected to forma middle connection body. From top to bottom of the middle connectionbody, there are external control fuel duct, external spray fuel duct,internal control fuel duct and internal fuel spray duct. At the top ofthe external control fuel duct, it is external working stroke amplifierwhich is of a taper cavity. At the bottom of the external control fuelduct, it is the external control fuel cavity, the shape of which is anannular groove. At the top of the internal control fuel duct, there isthe internal working stroke amplifier which is of a taper cavity. Withinthe internal control fuel duct is equipped with internal control fuelcavity, at the bottom of the internal control fuel duct it is innerpressure chamber; Within the external control fuel duct it is equippedwith external control fuel cavity, at the bottom of the external controlfuel duct it is outer pressure chamber.

In the double-channel needle valve body, it's the sleeve structure ofthe needle valve hole, at the bottom of double-channel needle valve bodythere are internal fuel spray nozzle which connecting the external andthe internal casing hole, and external fuel spray nozzle whichconnecting the external and the external casing hole. In the middle ofthe external casing hole, it's an outer pressure chamber, and theexternal spray fuel duct from the middle connection body down to theexternal pressure chamber. The top of the external casing holeconnecting with the external control fuel cavity which is annular grooveshape of the bottom of the middle connection body. So, to form the firstspace used to be placed the external needle valve body, as the firstspace axial size is greater than the length of the external needle valvebod. The top of the internal casing hole connecting with internalcontrol fuel cavity which is cylinder shape of the bottom of the middleconnection body. So, to form the second space used to be placed theinternal needle valve body, as the second space axial size is greaterthan the length of the internal needle valve body.

The external spray fuel duct and the internal spray fuel duct areconnected respectively with two tubing fuel ducts of the dual-channelinjector body, so from two tubing fuel ducts to the external andinternal casing hole of the double-channel needle valve body formingdual-channel.

The bottom of the two laminated type piezoelectric actuatorsrespectively are embedded in the top mouth of the external control fuelduct and internal control fuel duct of the middle of the middleconnection body. Through the two laminated type piezoelectric actuators,the pressure difference between the fuel pressure of the fuel controlcavity and the fuel pressure of the inner pressure chamber or outerpressure chamber are controlled. So to control the open or close stateof the internal or external needle valve, in turn to control theinjection action of the internal fuel spray nozzle or external fuelspray nozzle.

Compared with the existing technologies, the advantages of the inventionare:

-   -   1. This dual-channel piezoelectric injector uses laminated type        piezoelectric actuator driving directly, which makes the        injector work more quickly and therefore improves sensitivity of        the injector. It is better than the electromagnetic valve        control injector and indirect piezoelectric actuator control        injector.    -   2. The dual-channel piezoelectric injector can realize the        function that the different fuel can be injected in cylinder for        many times, and there are no more specific requirements for the        physical characteristics of the fuel.    -   3. For the dual-channel piezoelectric injector, we can change        the angle of the fuel injection when two nozzles inject at the        same time through the function of two fuel spray collision and        interference.    -   4. Using the dual-channel piezoelectric injector can eliminate        excrescent mounting hole structure used in direct injecting and        simplify the complexity of the cylinder head. At the same time,        It can reduce the costs of the manufacture and application.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a dual-channel piezoelectric injector ofthe invention;

FIG. 2 is a top view of the injector in FIG. 1;

FIG. 3 is a bottom plan view of the injector in FIG. 1;

FIG. 4 is a left side-sectional view of the injector in FIG. 1;

FIG. 5 is a back sight composite side-sectional view of the injector inFIG. 1;

FIG. 6 is a top view of the dual-channel needle valve body 1 in FIG. 4;

FIG. 7 is a side-sectional view of the dual-channel needle valve body 1in FIG. 4;

FIG. 8 is a side-sectional view of the dual-channel needle valve body 1in FIG. 5;

FIG. 9 is a side-sectional view of the external needle valve body 3 inFIG. 4;

FIG. 10 is a side-sectional view of the lower intermediate 4 in FIG. 4;

FIG. 11 is a side-sectional view of the lower intermediate 4 in FIG. 4;

FIG. 12 is a side-sectional view of the upper intermediate 4 in FIG. 5;

FIG. 13 is a side-sectional view of the upper intermediate 4 in FIG. 5;

FIG. 14 is a perspective view of the laminated type piezoelectricactuator in FIG. 4;

FIG. 15 is a perspective view of the dual-channel injector body 9 inFIG. 1;

FIG. 16 is a bottom view of the dual-channel injector body 9 in FIG. 15;

FIG. 17 is a left view and side-sectional view of the dual-channelinjector body 9 in FIG. 15;

FIG. 18 is a rear view of the dual-channel injector body 9 in FIG. 15.

In the FIG.:

1—the dual-channel needle valve body

2—the internal needle valve body

3—the external needle valve body

4—the lower intermediate

5—the upper intermediate

6, 7—the laminated type piezoelectric actuator

8—the fixing sleeve

9—the dual-channel injector body

11—the internal fuel spray nozzle

12—the external fuel spray nozzle

13—the needle body bulkhead

14, 44, 57—the external spray fuel duct

16—the outer pressure chamber

31—the external needle valve seal cone surface

32—the external needle valve pressure-bearing surface

33—the external needle valve inner cylinder

40, 48—the inner needle valve guide hole

45, 55—the external control fuel duct

46—the external control fuel cavity

47, 54—the internal spray fuel duct

49—the inner pressure chamber

51—the internal working stroke amplifier

53—the external working stroke amplifier

56—the internal control fuel duct

58—the internal control fuel cavity

61—the actuator seal body

62—the actuator pressure-bearing body

63—the terminal

91—the injector fixed slot

92—the terminal slot

93—the fuel tubing interface

94—the fuel tubing seal body

95—the terminal mounting holes

96—the internal fuel cavity

97—the external fuel cavity

98—the tubing fuel duct

99—the body bulkhead

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS OF THE INVENTION

The present invention is further described in conjunction with variousembodiments of the invention.

As shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5, the invention ofthe dual-channel piezoelectric injector is mainly composed of thedual-channel needle valve body 1, an internal needle valve body 2, anexternal needle valve body 3, a lower intermediate 4, an upperintermediate 5, two laminated type piezoelectric actuators 6 and 7, afixing sleeve 8, and a dual-channel injector body 9.

The dual-channel injector body 9 is at the bottom of it successivelyconnected with the upper intermediate 5, the lower intermediate 4 andthe double-channel needle valve body 1. At the top of the dual-channelinjector body 9 there are two tubing interfaces 93, and each tubinginterface 93 has a tubing fuel duct 98. There are two laminatedpiezoelectric actuators and two spray fuel ducts connected with twotubing fuel ducts respectively in the dual-channel injector body 9, asshown in FIG. 5 and FIG. 18.

As shown in FIG. 4, the characteristic of the dual-channel piezoelectricinjector is illustrated: the positioning and connection of the injectorbody 9, upper intermediate 5, lower intermediate 4 and double-channelneedle valve body 1 use a positioning pin and positioning holestructure, using the fixing sleeve 8 and thread structure to make surethe injector body 9, upper intermediate 5, lower intermediate 4 anddouble-channel needle valve body 1 closely are combined with each other.

As shown in FIG. 4, FIG. 8, FIG. 10, FIG. 11, FIG. 12 and FIG. 13, theupper intermediate 5 and lower intermediate 4 are connected with eachother to form the middle connection body. From top to bottom of themiddle connection body, there are the external control fuel duct 45 and55, the external spray fuel duct 44 and 57, the internal control fuelduct 56 and the internal spray fuel duct 47 and 54. At the top of theexternal control fuel duct 55, there is an external working strokeamplifier 53 which is a taper cavity. At the bottom of the externalcontrol fuel duct 45, there is an external control fuel cavity 46, theshape of which is an annular groove. At the top of the internal controlfuel duct 56, there is an internal working stroke amplifier 51 which isa taper cavity. Within the internal control fuel duct is equipped withinternal control fuel cavity 58, and at the bottom of the internalcontrol fuel duct 56 there is an inner pressure chamber 49; Within theexternal control fuel duct, it is equipped with external control fuelcavity 44, and at the bottom of the external control fuel duct 44 thereis an outer pressure chamber 16.

As shown in FIG. 6, FIG. 7 and FIG. 8, in the double-channel needlevalve body 1, there is the sleeve structure of the needle valve hole. Atthe bottom of the needle valve hole there is an internal fuel spraynozzle 11 which is connected with the external and the internal casinghole and external fuel spray nozzle 12 which is connected with theexternal and the external casing hole. In the middle of the externalcasing hole, there's an outer pressure chamber 16, and the externalspray fuel duct runs from the middle connection body down to the outerpressure chamber 16. The top of the external casing hole is connectedwith external control fuel cavity which is annular groove shape of thebottom of the middle connection body. So, to form the first space usedto be placed the external needle valve body 3, as the first space axialsize is greater than the length of the external needle valve body 3. Thetop of the internal casing hole is connected with internal control fuelcavity which is cylinder shape of the bottom of the middle connectionbody. So, to form the second space used to be placed the internal needlevalve body 2, as the second space axial size is greater than the lengthof the internal needle valve body 2.

As shown in FIG. 5 and FIG. 18, the external spray fuel duct and theinternal spray fuel duct are connected respectively with two tubing fuelducts 98 of the dual-channel injector body 9, so from two tubing fuelducts to the external and internal casing hole of the double-channelneedle valve body 1 forms the dual-channel.

As shown in FIG. 14, the characteristic of the laminated typepiezoelectric actuators 6 or 7 is made of actuator seal body 61,actuator pressure-bearing body 62 and terminal 63 connected to thecontrol circuit. The bottom of the two laminated type piezoelectricactuators 6 and 7 respectively are embedded in the top mouth of theexternal control fuel duct 55 and internal control fuel duct 56 of themiddle of the middle connection body. Through the two laminated typepiezoelectric actuators 6 and 7, to control the pressure differencebetween the pressure of the fuel control cavity and the pressure of theinner pressure chamber 49 or outer pressure chamber 16. So, to controlthe open or close state of the internal or external needle valve, and inturn to control the injection action of the internal fuel spray nozzle11 or external fuel spray nozzle 12.

The inner channel fuel way of the present invention is: Internal channelcontrol fuel way is composed of the actuator seal body 61 located belowthe internal laminated type piezoelectric actuator 6, the internalworking stroke amplifier 51, the internal control fuel duct 56 and theinternal control fuel cavity 58. The internal channel spray fuel way iscomposed of the internal spray fuel duct 47 and 54, the inner pressurechamber 49, the internal needle valve seal cone surface (like theexternal needle valve seal cone surface 31), the internal needle valvepressure-bearing surface (like the external needle valvepressure-bearing surface 32) and the internal fuel spray nozzle 11.

The outer channel fuel way of the present invention is: External channelcontrol fuel way is composed of the actuator seal body 61 located belowthe external laminated type piezoelectric actuator 7, the externalworking stroke amplifier 53, the external control fuel duct 45 and 55and the external control fuel cavity 46. External channel spray fuel wayis composed of the external spray fuel duct 14, 44 and 57, the outerpressure chamber 16, the external needle valve seal cone surface 31, theexternal needle valve pressure-bearing surface 32 and the external fuelspray nozzle 12.

The isolation structure of the dual-channel fuel way described above:The body bulkhead 99 as shown in FIG. 15 is located at the commoncentral plane of the internal working stroke amplifier 51 and theexternal working stroke amplifier 53, and bottom surface of the bodybulkhead 99 seal contacts with the upper surface of the upperintermediate 5. In turn, to realize the isolation between the internalfuel cavity 96 and the external fuel cavity 97. The upper surface of theneedle body bulkhead 13 seal contact with the bottom surface of thelower intermediate 4, which to ensure the perfectly isolating betweeninner channel fuel way and outer channel fuel way. In addition, thespace design of the double-channel needle valve body 1, the lowerintermediate 4, the upper intermediate 5 make the inner channel fuelway, outer channel fuel way, control fuel way and spray fuel wayisolating.

The fixed and connection form of each connection part in the presentinvention are shown in FIG. 6, FIG. 10 and FIG. 11: the contact betweensurface between dual-channel needle valve body 1 and the lowerintermediates under 4 respectively is designed for positioning hole 15,41 to placing dowel pin A, used to implement precise localizationbetween the double-channel needle valve 1 and the lower intermediate 4;By the same token, the contact surface of the lower intermediate 4 andthe upper intermediate 5 have location hole the positioning hole on thelower intermediate 4 and the upper intermediate 5 (not shown) to placethe dowel B, used to achieve the precise localization of the lowerintermediate 4 and the upper intermediate 5. The fixing sleeve 8 throughthe screw thread structure closely linked double channel needle valvebody 1, the lower intermediate 4, the upper intermediate 5 and thedual-channel injector body 9 together.

The move action of the needle valve in the invention: The clearance fitbetween the external needle valve body 3 and the first space internalsurface i.e. the external needle valve inner cylinder 33 and the needlebody bulkhead 13 formed mobile vice. The clearance fit between theinternal needle valve body 2 and the second space internal surface i.e.the inner surface of the inner needle valve guide hole 40, 48 and theouter surface of the internal needle valve body 2 formed mobile vice.

The Working Principle of the Present Invented Dual-Channel PiezoelectricInjector:

As shown in FIG. 4, FIG. 5, FIG. 7, FIG. 8 and FIG. 17, there are twofuel tubing interfaces 93, a number of fuel tubing ducts 98, a bodybulkhead 99, an upper intermediate 5, a lower intermediates 4 and aneedle body bulkhead 13. Through the design of the seal, positioning anddrilling to form two independent and non-interference fuel dual-channelfuel way, and each of the fuel way includes a control fuel way and aninjection fuel way.

As shown in FIG. 4 and FIG. 14, the actuator seal body 61 of thelaminated type piezoelectric actuator 6, 7 respectively seal fit withthe external, internal working stroke amplifier. High pressure fuelexports of two working stroke amplifiers respectively connected to thetop surface of the internal and external of the needle valve to form twocontrol fuel way.

As shown in FIG. 5 and FIG. 18, with dowel locating double-channelneedle valve body 1, the lower intermediate 4 and the upper intermediate5 by sealing, positioning and drilling design to form two spray fuelway.

By changing the voltage value of the terminal 63 of the laminated typepiezoelectric actuator (6 or 7), we can control the shortened orelongate state of the laminated type piezoelectric actuator 6 or 7. Theactuator pressure-bearing body 62 is fastened to the dual-channelinjector body 9, when the laminated type piezoelectric actuator 6 or 7shortening, the actuator seal body 61 will move up. So this can reducethe pressure of the control fuel cavity (46 or 58), leading to thepressure of the chamber (16 or 49) bigger than it was before, realizingthe needle valve body (2 or 3) moving up and injecting fuel. When thelaminated type piezoelectric actuator (6 or 7) expands, the actuatorseal body 61 will move downwardly. So this can increase the pressure ofthe control fuel cavity (46 or 58), leading to the pressure of thechamber (16 or 49) little than it was before, realizing the needle valvebody (2 or 3) moving down and stopping inject fuel.

Through the working stroke amplifier (51 or 53), the small variation ofthe laminated type piezoelectric actuator (6 or 7) is magnified and turnto the displacement of the needle valve body (2 or 3), and then, tocontrol the effective opening and closing of the needle valve.

The Fuel Injection Control Process of the Dual-channel PiezoelectricInjector:

The injection control of the internal channel fuel duct: When thelaminated type piezoelectric actuator 6 contracts, the pressure of theinternal control fuel duct 56 will be less than the pressure of theinternal spray fuel duct (47,54), and then the internal needle valvesealing cone surface (like the external needle valve seal cone surface31) will lift the double-channel needle valve body 1, the first highpressure fuel will arrive at the internal fuel spray nozzle 11, finallyrealizing internal channel injection. When the laminated typepiezoelectric actuator 6 expands, the pressure of the internal controlfuel duct 56 will be greater than the pressure of the internal sprayfuel duct(47,54), and then the internal needle sealing cone surface willseal contact with the double-channel needle valve body 1, finallystopping internal channel injection.

The injection control of the external channel fuel duct: When thelaminated type piezoelectric actuator 7 contracts, the pressure of theexternal control fuel duct (45,55) will be less than the pressure of theexternal spray fuel duct (14,44,57), and then the external needle valvesealing cone surface 31 will lift the double-channel needle valve body1, the second high pressure fuel will arrive at the external fuel spraynozzle 12, finally realizing external channel injection. When thelaminated type piezoelectric actuator 7 expands, the pressure of theexternal control fuel duct (45,55) will be greater than the pressure ofthe external spray fuel duct (14,44,57), and then the external needlesealing cone surface 31 will seal the double-channel needle valve body1, finally stopping internal channel injection.

In this invention, the size of the dual-channel piezoelectric injectoris as big as ordinary injector. This invention eliminatesdual-mounting-hole structure is adopted in the dual fuel directinjection engine, and simplifies the complexity of the cylinder cover.The present invention integrates dual fuel or single fuel double fuelrail injection into an organic whole, which can realize the dual fuel orsingle fuel with different injection pressure injected in cylinder formany times, at the same time it can reduce the costs of manufacture andapplication.

When we want to inject fuel earlier we can use the internal fuel spraynozzle 11, therefore, we can avoid or reduce the wet wall phenomenon.When two nozzles inject at a time, we can use the function of the twofuel beam collision and interference which can realize the change of thefuel injection angle, and to further avoid early wet wall phenomenon.The present invention can provide the better injection characteristicsand meet the need of dual fuel engine and dual track engine.

In combination with drawings, we have described this invention indetail. But the specific embodiment of the present invention is notlimited to the above method. Rather, the specific embodiment of theabove method is just schematic, rather than restrictive. The commontechnology person in the field of under the enlightenment of the presentinvention, in the case of not out of the present invention principle,still can make a lot of modification, these all fall within theprotection scope of the invention.

What is claimed is:
 1. A dual-channel piezoelectric fuel injector,comprising a dual-channel fuel injector body 9, wherein: the bottom ofthe fuel injector body 9 is successively connected with an upperintermediate 5, a lower intermediate 4 and a double-channel needle valvebody 1; at the top of the dual-channel injector body 9, there are twotubing interfaces 93, and each tubing interface 93 has a tubing fuelduct 98; there are two laminated piezoelectric actuators and two sprayfuel ducts connected with two tubing fuel ducts respectively inside thedual-channel injector body 9; the upper intermediate 5 and lowerintermediate 4 are connected with each other to form a middle connectionbody; the middle connection body top-down contains an external controlfuel duct (45,55), an external spray fuel duct (14,44,57), an internalcontrol fuel duct (47,54) and an internal spray fuel duct 56; at the topof the external control fuel duct (45,55), there is an external workingstroke amplifier 53 which is of a taper cavity; at the bottom of theexternal control fuel duct 55, there is an external control fuel cavity46, which is of an annular groove shape; at the top of the control fuelduct 56, there is an internal working stroke amplifier 51 which is of ataper cavity; within the internal control fuel duct, it is equipped withan internal control fuel cavity 58, while at the bottom of the internalcontrol fuel duct 56 it is an inner pressure chamber 49; within theexternal control fuel duct it is equipped with an external control fuelcavity 44, while at the bottom of the external control fuel duct 44 itis an outer pressure chamber 16; in the double-channel needle valve body1, there is sleeve structure of the needle valve hole; at the bottom ofthe needle valve hole there is an internal fuel spray nozzle 11 whichconnects with the external and the internal casing hole and externalfuel spray nozzle 12 which connects with the external and the externalcasing hole; in the middle of the external casing hole there's an outerpressure chamber 16, the external spray fuel duct running from thedescribed middle connection body down to the described outer pressurechamber 16; the top of the external casing hole connects with externalcontrol fuel cavity which is of an annular groove shape of the bottom ofthe middle connection body; to form the first space used to be placedthe external needle valve body 3, as described the first space axialsize is greater than the length of the external needle valve body 3; thetop of the internal casing hole connecting with internal control fuelcavity which is cylinder shape of the bottom of the middle connectionbody; to form the second space used to be placed the internal needlevalve body 2, as described the second space axial size is greater thanthe length of the internal needle valve body 2; the described theexternal spray fuel duct and the internal spray fuel duct connectsrespectively with two tubing fuel ducts 98 of the dual-channel injectorbody 9, so from two tubing fuel ducts to the external and internalcasing hole of the double-channel needle valve body 1 it formsdual-channel; the bottom of the two laminated type piezoelectricactuators 6 or 7 is respectively embedded in the top of the externalcontrol fuel duct 55 and internal control fuel duct 56 of the middleconnection body; the two laminated type piezoelectric actuators areusedto control the pressure of the fuel in the fuel control cavity 46 or 58;pressure difference is formed between the high pressure fuel pressure ofthe fuel control cavity 58 or 46and the pressure of the inner pressurechamber 49 or the pressure of outer pressure chamber 16, which can openor close the internal and external needle valve of the double-channelneedle valve body 1, and further to control the injection action of theinternal fuel spray nozzle 11 and the external fuel spray nozzle
 12. 2.The injector according to claim 1, wherein the positioning andconnection of the fuel injector body 9, the upper intermediate 5, thelower intermediate 4 and the double-channel needle valve body 1 areachieved by using positioning pin and positioning hole cooperatively;the fixing sleeve 8 and thread structure are used to make the fuelinjector body 9, the upper intermediate 5, the lower intermediate 4 andthe double-channel needle valve body 1 closely combined with each other.3. The injector according to claim 1, wherein the laminated typepiezoelectric actuator 6 is made of an actuator seal body 61, anactuator pressure-bearing body 62 and a terminal 63 connected to thecontrol circuit.
 4. The injector according to claim 1, wherein thecooperation between the external needle valve body and the internal wallof the first space is clearance seal fit; the cooperation between theinternal valve body and the internal wall of the second space isclearance seal fit.
 5. The injector according to claim 1, wherein theinternal needle valve body 2 has an internal needle valve seal conesurface and an internal needle valve pressure-bearing surface; theexternal needle valve body 3 has an external needle valve seal conesurface, an external needle valve pressure-bearing surface and anexternal needle valve inner cylinder.